Why do your samples include both a type description and data? I expected there would only be a description and no data.

Let's use the bcas.asn file that is shipped with most OSS ASN.1 Tools.

BCAS DEFINITIONS ::= BEGIN

BBCard ::= SEQUENCE {
name IA5String (SIZE (1..60)),
teamIA5String (SIZE (1..60)),
age INTEGER (1..100),
position IA5String (SIZE (1..60)),
handedness ENUMERATED {left-handed(0), right-handed(1), ambidextrous(2)},
batting-average REAL  --<DECIMAL>--
}

myCard BBCard ::= {
name "Casey",
team "Mudville Nine",
age 32,
position "left field",
handedness ambidextrous,
batting-average {mantissa 250, base 10, exponent -3}
}

END

It is true that in many applications you will decode ASN data and then manipulate the data accordingly. Looking at the example above, the top part, BBCard, is the type definition; the bottom part, myCard, is the value definition, which is in what's called value notation.

An ASN.1 module may contain both type definitions and values, but the values are not necessary. Values are typically used as test cases and that's what it is in the file above. It is generated as an initialized struct in the .c file. If you wish to decode, you may ignore the value myCard; if you wish to encode, you may either (a) use the value myCard as a test case or (b) create your own test case by allocating and populating the BBCard struct.

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The samples included with some of the Knowledge Center answers are meant for your general understanding of the OSS products. Different versions of the products might produce slightly different outputs. Consult the products documentation and samples for the most up-to-date products information and code examples.